Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2005
Publication Date: 2/10/2006
Citation: Solomon, E.B., Huang, L., Sites, J.E., Annous, B.A. 2006. Thermal inactivation of salmonella on cantaloupes using hot water. Journal of Food Science. 71(2): M25-M30.
Interpretive Summary: Cantaloupe melons have been implicated in at least six outbreaks of Salmonellosis since 1990. Our laboratory has investigated a variety of treatments for sanitizing melons, concluding that aqueous sanitizers were only partially effective at reducing populations of Salmonella, especially when the target bacteria were allowed to reside on the melon surface for more than 24 hours. Recently, our laboratory has focused on the use of hot water as a simple intervention to inactivate surface associated bacteria. The goal of the current research was to demonstrate the efficacy of hot water using specific temperatures and durations for the inactivation of Salmonella and to model the penetration of heat from water at various temperatures into the flesh of test melons. Results confirmed that 99.999% reduction of pathogen populations could be obtained and that the edible portions of melons remain relatively cool while the rind temperature rapidly rises to a point lethal for Salmonella. These results indicate that surface pasteurization will enhance the microbiological safety of cantaloupes while maintaining the quality of the product. These findings will assist food industry and regulatory agencies in establishing processing guidelines to guard against pathogens, thereby decreasing the incidence of food poisoning outbreaks.
Technical Abstract: The inactivation of Salmonella on cantaloupes using hot water was investigated. Whole melons, inoculated with a cocktail of Salmonella isolates, were subjected to thermal treatments of various lengths in water at 65, 75, and 85 °C. Treatment with water at 85 °C for 60 seconds resulted in reductions of ca. 4.6 log CFU per square centimeter of rind. Thermal penetration profiles were measured and simulations conducted to verify the effect of hot water treatment conditions on the temperatures to which Salmonella attached to the surface of cantaloupe melons are exposed. Experimental and simulation data indicated that the internal temperature of melons treated with hot water did not increase rapidly compared to the rind temperature. Edible flesh 10 mm from the surface of the rind remained cool regardless of the process temperature. These results show the utility of hot water for the inactivation of Salmonella on cantaloupes and provide a framework to producers of fresh-cut melon for the potential use of hot water as an intervention treatment.